A turbocharger system operates to allow more power to be produced from an internal combustion engine. A turbocharger typically includes a turbine wheel and a compressor wheel mounted on a common turbine shaft. During operation, exhaust gas discharged from an exhaust manifold of the internal combustion engine drives the turbine wheel which rotates the turbine shaft at relatively high speed along with an associated thrust bearing system in the center housing of the turbocharger system. This rotational momentum and the input airflow subsequently rotates the mounted compressor wheel. The compressor then compresses the input air and provides compressed air at a boosted pressure to the inlet of the internal combustion engine, increasing the charge air density and hence amount of power that can be produced by the engine.
However, the inventors herein have recognized some issues with the above turbocharger system. A thrust load is generated on the turbine shaft due to the pressure imposed on the compressor and turbine's front and back faces. The back-faces of the compressor and the turbine generate maximum thrust, which causes axial loading of the shaft and increases friction loss of the contact seals and the associated thrust bearing system, reducing turbocharger durability and efficiency. Thrust loading may be particularly unbalanced in turbocharger systems that include axial turbines or an electric motor to drive the compressor.
Accordingly, a turbocharger system is provided herein to at least partly address the issue of the high pressure generated at the back-face of turbine wheels, which may cause excessive axial thrust load on the turbine shaft resulting in parasitic loss of the associated thrust bearing system. In one example, the turbocharger system comprises a centrifugal compressor including an impeller having a plurality of radiating blades coupled to a partial back plate. The partial back plate compressor has a plurality of cut-out sections. Each cut-out section is located between two respective radiating blades on an outer circumference of the impeller. The compressor is mounted on a shaft and coupled to a driver, mounted on the same shaft.
In this way, the high pressure at the back-face of the compressor is dissipated through the cut out sections from the back-face of the compressor to the front-face of the compressor, reducing axial thrust load on the shaft.
In another example, the above-described turbocharger system may include a regenerative turbocharger system including a back-to-back turbo pump with a back of a first impeller facing a back of a second impeller, a hydraulic turbine, a compressor, and a turbine, all mounted on a common shaft. The regenerative turbocharger system may generate thrust loading, exposing nearby seals to high pressure, and the inclusion of the back-to-back turbo pump may be used to generate balanced thrust load on the shaft.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.